Despite a social media uproar and multiplereportsfrom news outlets, the Pentagon probably hasn't contributed much to the strikingly military appearance of police responding to protests in a St. Louis suburb, sources tell CNBC—though another agency of the federal government may be.

Jeff Roberson | AP

A member of the St. Louis County Police Department points his weapon in the direction of a group of protesters in Ferguson, Mo. on Wednesday, Aug. 13, 2014.

Photos from Wednesday protests in Ferguson, Missouri, have invited comparisons to Egypt or Ukraine, with reports focusing on the police force's camouflage (most of which is designed for forest or desert terrain, despite Ferguson's suburban backdrop), body armor and armored vehicles.

Reports have pointed to the U.S. Department of Defense's so-called 1033 program, which allows local, state, and federal law enforcement agencies to acquire military surplus supplies for the cost of shipping and maintenance. That program is real, but experts told CNBC that it's largely unrelated to the police arms and equipment being used in Ferguson.

"It's crazy that they say the Pentagon is adding any kind of fuel to that fire," said a Department of Defense source, who declined to give his name as he was not authorized to share his opinion on the subject. "We're providing a service to the taxpayer."

The source said that what media reports have identified as a military-issued Mine Resistant Ambush Protected (MRAP) vehicle in Ferguson is actually a much smaller privately sold vehicle called a BearCat. The vehicle cannot be obtained through the Pentagon's program and instead needs to be purchased by the department, he said.

That assertion was backed up by Mike O'Connell, a spokesman for the Missouri Department of Public Safety, who said he did not have any records of St. Louis County police receiving any armored vehicles through the Pentagon's program.

That said, weapons and equipment may have been provided by the Pentagon's program to the departments helping to police the Ferguson protests, the DOD source said. Nearly every local department in the country has taken advantage of the program, which provides everything from desk lamps to rotary aircraft, he added.

Grants from Homeland Security

Even the body armor and smaller rifles used by the officers policing the Ferguson protests are probably not provided by the Pentagon, said Tom Aveni, the director for the Police Policy Study Council. Agencies will typically spend their own budgets on those items, or rely on grants from the federal government, he explained.

Those grants—the vast majority of which come from the Department of Homeland Security, ostensibly to combat terrorism in the wake of the Sept. 11, 2001, attacks—largely explain the equipment seen in the Ferguson protests response, police and Pentagon sources say.

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A police officer keeps watch over demonstrators protesting the shooting death of teenager Michael Brown on August 13, 2014 in Ferguson, Missouri.

The presence of the BearCat armored vehicles and SWAT equipment may well be doing more harm than good, said Chuck Drago, the former Oviedo, Florida, police chief and a police consultant for Drago Professional Consultants.

"I would not bring [armored vehicles] out in the beginning when you have a peaceful demonstration. It gives the sense that you're ready to attack," Drago said. "You're not at war, you're a civil police, this is your population. There's no reason to militarize to this level."